When being applied to deep treatment of sewage, the constructed wetland system has the advantages of low construction and operation costs, convenient operation, strong treatment capacity, combined landscape and ecological benefits and the like. The sewage treatment of the constructed wetland is completed under the coaction of microbial degradation, plant absorption, filler adsorption and the like. Compared with a surface flow wetland, due to the water flow pattern and the structural characteristics, the subsurface flow constructed wetland improves the sewage purification ability of microbes, and can reduce the influence of seasonal changes and the breeding of mosquitoes and flies, so application of the method is increasingly wide. However, the filler clogging problem of the subsurface flow constructed wetland has seriously affected the sustainable operation of the system.
Previously, prejudgment methods for constructed wetlands include an observation method, a clogging material sampling determination method, a permeability coefficient determination method, a tracer determination method and the like. These methods all have great defects in the process of popularization and application, wherein the observation method has serious hysteresis; the clogging material sampling determination method has a strong destructive effect on the wetland bat the permeability coefficient method is limited to the determination of a certain point, and is relatively complex in operation; and the tracer method only can be used for overall evaluation on the wetland, and may take a long time and produce secondary pollution.
In recent years, the clogging of a constructed wetland is positioned using resistivity difference in some studies. This method is based on the resistivity difference between a clogged region and an unclogged region. The previous studies directly measured the resistivity during wetland operation. It is generally believed that the dogged region of the constructed wetland has higher resistivity, whereas the unclogged region has the characteristic of lower resistivity. Since clogging materials usually contain more than 90% of water, the significance of the resistivity difference between the dogged and unclogged regions shall be further evaluated.
At present, the studies on the clogging of the constructed wetland are still being perfected. Positioning of the clogged region of the subsurface flow wetland and determination of the degree of clogging are crucial. The mastery of the basic information can provide a powerful technical support for preventing regional clogging deterioration and governing regional clogging.